The present invention relates generally to athletic shoes including running shoes, aerobics class exercise shoes, cross-training shoes and specialized sports shoes such as tennis shoes and basketball shoes having a built-in capability of accurately measuring the useful life of the shoe and indicating the need for shoe replacement to the user. The device is placed in a shoe during manufacture or assembly. It has a built-in, electronic component sole wear indicator capable of showing shoe sole wear, remaining useful life of the shoe and advising the user when to replace the shoe.
Consumers of shoes, particularly athletic shoes, need to know when the shoes have lost their shock-absorbing capability and therefore, need to be replaced. Consumers will benefit by knowing when their athletic shoes need to be replaced with a new pair. On one hand, premature replacement creates an unwarranted expense, while on the other hand, delayed replacement can cause pain and lead to injury. For example, one authority places the useful life of a running shoe at between 300 and 500 miles (Running Injury Free, Ellis and Henderson, Rodale Press, 1994). Running shoes range in price from $60.00 to over $100.00 Premature replacement, for example at 200 miles, generates unnecessary expense. However, running on xe2x80x9cspentxe2x80x9d shoes can cause pain and injury, particularly in athletic applications and as people age. Therefore, consumers would benefit from an athletic shoe with the herein described wear indicator inside, a shoe equipped with an internal, unobtrusive device which reports both economic utility and functional utility of the shoe have been utilized.
Shoe wear indicators are known to the art. U.S. Pat. No. 5,894,682 issued to J. Broz discloses a built-in wear indicator comprised of a shoe having an outsole made of durable material to withstand contact and wear and a midsole made of cushioning material to absorb shock. The wear indicator consists of plugs of a less compactable material (i.e. a material that has a slower rate of breakdown, a smaller loss of resiliency and less compaction) installed in several locations in the midsole and extending into the outsole. According to Broz, as the midsole material breaks down and loses its ability to absorb shock, it compacts and contracts in the vertical dimension. The wear indicator, by virtue of breaking down more slowly and losing its compressibility less rapidly, retains its vertical dimension and consequently projects further out from the bottom of the midsole into the outsole in response to wear. With extended wear, the protrusion of the built-in wear indicator device into the outsole becomes detectable to the wearer upon inspection of the bottom of the shoe.
The device of the present invention measures wear. Such measurement is provided with a built-in electronic component wear indicator device that is more accurate than the device described in U.S. Pat. No. 5,894,682 because it is insensitive to terrain differences and does not rely upon outsole wear or midsole compaction. The invention does not rely on midsole material compaction is important because many athletic material midsoles include both elastic materials and pressurized gas or fluids. Thus, measuring midsole material compaction alone may not provide information when a fluid-filled bladder containing gas or liquid has lost its shock absorbing capacity. Further, it does not disturb the integrity of an athletic shoe""s midsole or outsole as may be the case with multiple sole plugs of a less compactable material than the midsole installed about the midsole. In fact, one embodiment of the present invention is a thin strip of tape having electronic components disposed thereon which is placed between the midsole and outsole during the manufacturing process. Because of the very small size it does not intrude upon the integrity and performance characteristics of the shoe and is very easily installed between the midsole and outsole during the manufacturing process.
U.S. Pat. No. 3,578,055 to French et.al. discloses a tread wear indicator for automobile tires and U.S. Pat. No. 3,929,179 to Hines discloses a tread wear indicator device also incorporating the wear indicator into a tire. These devices measure tire life by assessing the physical wearing away of the tread similar to Broz""s method of measuring midsole wear in a shoe.
Shoe step counting devices are found in the prior art. U.S. Pat. No. 4,019,030 to Tamiz discloses a mechanical device for counting and recording the number of steps taken by a pedestrian. An operating member projects below the heel and initiates actuation of a digital counter each time the heel is brought into contact with the ground. The objective of the invention is to measure distance traveled by noting the number of steps taken at the beginning and end of a walking session.
U.S. Pat. No. 4,402,147 to Wu discloses a shoe with a switch operatively arranged to produce an electrical signal in response to a user taking a step, an electronic counter means for counting electrical signals from the switch and an electronic display to show total number of steps taken and therefore, the distance traveled. U.S. Pat. No. 5,471,405 to Marsh discloses a measuring device embedded in a shoe that provides a force analysis that is recorded and used to determine real time force analysis calculations for the user.
One embodiment of the present invention measures steps taken by a user. The purpose of counting steps is to measure sole wear or, more specifically, the progressive fatigue of the midsole material and/or the loss of shock absorbing capability of either gas or liquid filled bladder. In one embodiment an ASIC (application specific integrated circuit) capable of counting, remembering and communicating the number of steps taken will be preset to the specific shoe application. A wear-indicator display visible to the user will show the progressive deterioration of the shoe as it progresses through its useful life. Similar in principle to an automobile fuel gauge the user will know when the shoe should be replaced.